The present invention relates to a head box or flow box for a paper making machine. A fibrous suspension of pulp is sprayed from the head box onto a wire screen web, called a wire. The head box includes a chamber having an outlet duct. Partition walls are arranged in the outlet duct and are supported on the side walls of the head box chamber. The partition walls extend generally in the direction of flow of the suspension.
The head box or flow box in British Pat. No. 1,457,667 has a partition wall that is located in the stream of suspension. That wall is rigidly fastened to a horizontal cross member between the opposed vertical side walls of the flow box chamber. It is desirable to obtain a flow of the suspension which is as homogeneous and uniform as possible over the entire width of the head box as well as within the width of the slot at the flow outlet (layer thickness). For this purpose, it may be necessary to shift the supported positions of the partition walls in certain directions and within certain limits. The partition walls must be movable either transverse to the direction of flow to change the width of the outlet duct or along the direction of flow in order to change the flow conditions at the pulp outlet, or in a combination of both directions.